Embodiments of the invention relate generally to electrical wire connections and, more particularly, to wire terminal blocks and an associated mounting/installation mechanism for the addition of such terminal blocks to components of an electrical control system.
Electrical switching components are generally well known in the art and include, for example, circuit switching devices and circuit interrupters, such as circuit breakers, contactors, motor starters, motor controllers, operator switches and other load controllers. It is typical for such electrical switching components to include built-in physical features for the mounting of auxiliary devices or accessories thereto. These physical features are used with devices designed specifically to report or indicate information about the component they are attached to. For example, contactors have auxiliary contacts to report the status of the contactor (i.e., closed or open), operator elements have contacts that indicate the position or mode of the operator element, (i.e., left, center, or right), and circuit breakers or overloads have contacts that indicate if the device is closed, open, or tripped.
Typically, electrical control assemblies that use electrical switching components are contained within enclosures or mounted on panels that are effective to protect the electrical components from exposure to environmental conditions or to protect the operator. As an example, a contactor and motor starter may be housed in a common enclosure, with an operator switch also provided thereon. In such electrical control assemblies, it is common for one or more spare terminal blocks or other wire connection accessories to be included in the enclosures. With respect to such spare terminal blocks, such blocks are employed to provide needed isolated wire connection points for internal and external electrical wire connections as it is recognized that it may be necessary to provide isolated terminal blocks to land unterminated wires that are present within the enclosure—to meet safety requirements/regulations, etc.
For purposes of mounting such terminal blocks and other accessories within the enclosure, various rail structures or mechanical fasteners (i.e., screws, bolts) are often utilized. One such popular rail structure is based upon a standard set of flanged rails that can be cut to a desired length and attached via screws to the interior of an enclosure. The rails, commonly referred to as “DIN” rails, have either inwardly or outwardly projecting raised flanges along their length for receiving the terminal blocks/accessories thereon thereon, with the terminal blocks/accessories featuring corresponding structures designed to interface with the rail flanges to hold them securely in place to the enclosure or panel during installation and use.
With regard to the use of such DIN rails and the mounting of terminal blocks thereon, that there is a cost associated with the components and the labor necessary to secure each component to the enclosure or panel with the associated hardware. In addition, it is recognized that the installation of the DIN rails and securing of components thereto, in many cases, is required to be performed as an update or retrofit in the field after the assembly has been manufactured and installed. Because the assembly is no longer at the factory, the tools and methods needed (e.g., drilling holes, rewiring) to install this may not be easily accomplished at other locations.
In addition to the cost and expense in material and labor of affixing the DIN rail to the enclosure and installing the terminal blocks/accessories thereon, it is recognized that the inclusion of the DIN rail and mounting of components thereon consumes a large amount of space in the enclosure. That is, spacing within the enclosure is often at a premium, and the DIN rail and terminal blocks/accessories mounted thereon may take up valuable space within the enclosure or panel that would ideally be left free and/or prevent the use of a smaller enclosure or panel at a lower cost to provide the same function were the DIN rail not present. The lack of panel space or mounting locations for the addition of these components in the field is also a common problem.
It would therefore be desirable to provide for the additional electrical connection points/mounting of terminal blocks and other wire connection accessories within the enclosure in a fashion that does not require use of DIN rails or other mechanical fasteners, to minimize the labor and expense associated with installing these parts and affixing components thereto. It would also be desirable for the terminal blocks/accessories to be mounted in a manner and at locations that minimizes the amount of space within the enclosure or panel taken up thereby.